Blackstone’s Ratio

“Better that ten guilty persons escape than that one innocent suffer.”

– William Blackstone

Blackstone was an 18th century British lawyer, judge, and member of parliament. He was conservative both politically and morally, seeing morals and the law as set down by god. “No human laws,” he said, “are of any validity if contrary to [the law of god].” In 1754 Blackstone published Analysis of the Laws of England, a seminal work on the history of British law and the substantive principles on which it was based. In 1765 Blackstone published a follow-up book, Commentaries on the Laws of England from which the above quote is taken.

Blackstone’s ratio is well known, becoming part of Anglo-American jurisprudence. He did not invent the idea of placing higher priority on protecting the innocent. His ratio of innocent to guilty is rather stingy. Maimonides, the 12th century Jewish philosopher said that “it is better and more satisfactory to acquit a thousand guilty persons than to put a single innocent one to death.” Maimonides is ten times more compassionate than Blackstone. Also more compassionate was Benjamin Franklin who correctly understood that he was expressing a venerable idea.

Regardless, the ratio is an important principle in law and morality. When pursuing and punishing the guilty outweighs concern that we are not unjust to to the innocent, we lose something very precious. The purpose of the law is to defend people. If we are not horrified at the prospect of causing undeserved suffering, then we are contrary to the whole purpose of the law. Blackstone’s Ratio (and Maimonides’s and Franklin’s ratios) are essential reminders of our essential humanity.